Hardware costs can be more easily managed, since almost everything will reside in the data center.
Pro: Instead of buying a raft of PCs that will be scattered around the office--or even outside the office if you’re supporting a mobile workforce or employees who work remotely--you'll acquire one premium system with redundant power supplies, a UPS, high-performance storage, and high-bandwidth networking that will deliver capable hardware to all users equally.
Con: Procuring one big server means a large initial outlay, versus inexpensive PCs that can be acquired in stages or upgraded a few at a time. If that one server goes down, every user relying on that machine will be unable to work. If a single PC goes down, only one user is impacted.